Neck seals used in survival suits and dry suits are generally made of tight fitting neoprene or latex to provide a seal against the ingress of water when the user is submerged. The tight fit that is required to ensure the sealing function makes them uncomfortable to wear and restricts neck and head movement. Furthermore, the permanent seals at the extremities of these garments prevent the exchange of air, giving rise to the possibility of overheating when the user is not submerged.
Naval aviators generally wear specially designed survival suits as part of their flight gear because most of their flying is done over water. They often spend hours in the cockpit or helicopter bay during the performance of their missions. One of the most common complaints with respect to their equipment is the lack of comfort that is a characteristic of current neck seal technology. The tight fit of conventional neck seals restricts head movement and presses on the throat, which can eventually hamper communication. If the fit is too tight it can even affect circulation. Attempts have been made to design seals that allow for head movement. One design features a latex neck seal with a bellows section. In principle this should solve the mobility problem, but in practice the folds of the bellows tend to limit movement, particularly twisting of the neck, because of high friction between self-contacting parts of the device. Another design is the simple neoprene neck seal commonly used in many body suit applications. While more comfortable to wear than latex, the neoprene seal must be tight to ensure a seal during submersion, resulting in a tight fit even when the user is not in the water. Neither of these designs addresses airflow.
Various attempts have been made at solving the sealing problem in a variety of fields and applications. For example, U.S. Pat. No. 3,731,319 to O'Neill discloses a diving suit in which seals around the neck, wrists, and ankles are formed by folding inwardly the fabric around these extremity openings to create a tight seal against the skin. This approach is similar to many existing tight fitting seals, and does not suitably address user comfort. Other examples of tight fitting seals include U.S. Pat. No. 6,415,449 (survival garment with neck seal, wrist seals, and ankle seals made of an elastic material); U.S. Pat. No. 3,958,275 to Morgan et al. (diving helmet with neoprene or rubber neck dam supported by a rigid plate); and U.S. Pat. No. 4,015,295 to Lancaster et al. (neck seal having multiple rigid parts).
U.S. Pat. No. 5,802,609 to Garofalo discloses a diving suit that uses a ring of elastomeric material to form a toroidal seal around the arm, leg, and neck openings of a dry suit. In Garofalo, the seal is formed by a hem that is folded inwardly and secured to form a tubular pocket that contains a tape-like elastomeric ring as a stiffening element. As a result, pressure from the tight fitting suit is concentrated underneath the ring, forming a toroidal seal section. In Garofalo, this pressure is always present and the seal does not distinguish between wet and dry conditions.
Attempts have also been made to solve the comfort problem in neck seals used in dry suits and survival suits. U.S. Pat. No. 6,668,386 to Vidal discloses an adjustable neck seal for use with dry suits which includes a flexible tube surrounding an opening, and an elastic pull cord positioned within the tube for adjusting the seal. In Vidal, the wearer can adjust the tightness of the neck seal as necessary. However, a user-adjusted neck seal is undesirable in garments that are used as safety devices, which are designed to function regardless of the state of consciousness of the wearer.
U.S. Pat. No. 4,365,351 to Doerschuck et al. discloses a design for neck and wrist seals that uses a thick open celled foam section with a watertight skin to provide the seal. The seals are cylindrical in external shape with inner surfaces that are conical and cylindrical. A conical section is bonded to the suit with non-stretch tape, and the remainder of the seal expands when the user pushed his hand or head through. Although this approach attempts to make the seals more comfortable, it does not offer any variation in seal fit between the dry and wet states and therefore is essentially a common tight fitting seal.
U.S. Pat. No. 5,647,059 to Uglene et al. discloses a design for an inflatable seal constructed in three layers. An inflatable layer is sandwiched between a deformable inner layer and a non-stretch outer layer that directs the expansion toward the neck. In Uglene et al., the seal is permanent once donned and is not activated or established by the presence of water. The approach utilized in Uglene et al. is simply aimed at making the donning and doffing easier and in providing some level of adjustability for the user to regulate his or her level of comfort. However, an inflatable design would be inappropriate in an application which requires functioning under emergency conditions. Using the design of Uglene et al., the wearer would need to consciously ensure that the neck seal is inflated, which would be impossible if the wearer became unconscious due to a crash or the like.
U.S. Pat. No. 6,082,360 to Rudolph et al. discloses a respiratory mask and seal. The seal is made of a hydrogel described as sticky, resilient, self-sustaining, and non-flowable. Although the class of material used in this seal is that of polymer hydrogels, the material used has no ability to change its form substantially in response to the presence of fluid. Moreover, such a hydrogel would be unable to develop a sealing pressure.
U.S. Pat. No. 6,240,321 to Janke et al. discloses an expandable seal for use with a medical device such as an implanted lead with an open lumen tip. The seal, which can be part of the tip or can be deployed separately, swells over time to limit the amount of fluid that enters the device. The hydrogel matrix in Janke is composed of a silicone and glycerol blend; in experiments, the amount of glycerol was varied between 10% and 40% by weight percentage, with the total amount of expansion being measured over 150 days. However, the silicone-glycerol blend utilized in Janke cannot be classified as a superabsorbent polymer, due to its low swelling ratio, i.e., an expansion of about four times the original volume over 150 days. Moreover, silicone-glycerol hydrogel seals would not be suitable for use in a body suit, because they do not satisfy the requirements of a fast swelling speed and a high degree of swelling.
U.S. Pat. No. 6,698,510 to Serra et al. discloses a thermal regulation device that uses a reversible, thermosensitive hydrogel embedded in a foam matrix to control the rate of water flow in a wet suit. The mechanism works by regulating the permeability of a water transport layer, thereby controlling the rate of flow and, as a result, the convective heat transfer. The foam matrix with an embedded gel taught in Serra et al. could never form an effective seal because the structure of the foam matrix would always present a wicking path for the water to be transported through the structure. Although the foam matrix would be sufficient to significantly impact convection, it is not adequate for the purpose of providing a seal.
It would be desirable to provide an improved sealing device and sealing method for use in body suits, for forming a seal in response to a change of environmental conditions, which possesses characteristics such as a fast swelling speed and a high degree of swelling. The sealing device and related methods should overcome the deficiencies of the presently available methods and systems.